Boston, MA – There is strong evidence that expanding health insurance increases access to care, improves health in a variety of ways, and reduces mortality, according to Harvard T.H. Chan School of Public Health researchers who analyzed a decade’s worth of evidence on the effects of insurance coverage on health.

The review—the most current analysis of its kind—will be published online June 21, 2017, in the New England Journal of Medicine.

As the national debate continues over the future of the Affordable Care Act (ACA), which has expanded health insurance to more than 20 million Americans, there has been intense debate about what effects, if any, insurance coverage has on health and mortality. The researchers sought to address that question.

“We know far more now about the effects of health insurance than we did when the ACA was originally passed, due to many recent high-quality studies. The evidence we reviewed in this paper shows that coverage makes a major difference in people’s ability to live healthier and longer lives,” said Benjamin Sommers, associate professor of health policy and economics at Harvard Chan School, associate professor of medicine at Harvard Medical School, and lead author of the paper. Co-authors included Atul Gawande, director of Ariadne Labs, professor of health policy and management at Harvard Chan School, and surgeon at Brigham and Women’s Hospital, and Katherine Baicker, C. Boyden Gray professor of health economics.

The Harvard Chan researchers synthesized the most rigorous evidence from the past decade, drawing on findings from more than 40 papers, including major studies of their own. The body of evidence showed that coverage expansions have produced significantly higher rates of being able to afford needed care, and having access to preventive services, primary care, chronic illness treatment, medications, and surgical care. In turn, these changes have led to a wide range of improvements in health. For example:

People who obtain health insurance coverage report significant improvement in their overall health, a generally consistent finding across studies of Medicaid expansion, private insurance expansion, Massachusetts health reform, and the ACA. The authors noted that research also shows that better self-reported health is associated with lower mortality rates.

Insurance has major benefits for people with depression—one of the most common chronic conditions in the U.S.—including improved rates of diagnosis and treatment and reduced symptoms.

Several large population-based studies of health insurance expansion find that it saves lives, with the largest reductions occurring among deaths from conditions that are frequently treatable with adequate medical care, such as infections, heart disease, and cancer.

Coverage expansions do not save money—they increase overall health spending—but are relatively cost-effective compared to other policies affecting mortality, according to a recent economic analysis.

The authors acknowledged that findings from many of the studies they reviewed are nuanced, and some are seemingly contradictory. The differences are due, at least in part, to major differences in study design or length or to the complexity of the links between insurance coverage and particular health effects. But across the multitude of studies, the authors found compelling evidence that health insurance leads to important but often gradual improvements in health and survival. People with health insurance are also more financially secure, with lower out-of-pocket spending and fewer medical debts. Thesegains must be weighed against the cost of financing public subsidies for insurance.

The authors conclude: “There remain many unanswered questions about U.S. health insurance policy, including how to best structure coverage to maximize health and value and how much public spending we want to devote to subsidizing coverage for people who cannot afford it. But whether enrollees benefit from that coverage is not one of the unanswered questions. Insurance coverage increases access to care and improves a wide range of health outcomes.”

Baicker’s work on the paper was supported by NIA (National Institute on Aging) grant R01 AG034151.